Matching canvas weave patterns from processing x-ray images of master paintings

Abstract

Thread counting algorithms seek to determine from x-ray images the vertical and horizontal thread counts (frequencies) of the canvas weave comprising a painting's support. Our spectral-based algorithm employs a variant of short-time Fourier analysis to the image domain that reveals isolated peaks at the proper vertical and horizontal frequencies. Paintings made on canvas sections cut from the same canvas roll have been hypothesized to have similar, distinctive weave characteristics, allowing art historians to more accurately date paintings. Spatial variation of weave frequency measurements across a painting were cross-correlated using a new measure to determine possible common weave patterns between pairs of x-rays. By analyzing a database of x-rays made from 180 paintings by van Gogh, our algorithms confirmed situations where paintings were known to have been made on canvases cut from the same roll and found new ones.

Automatic Thread-Level Canvas Analysis: A machine-learning approach to analyzing the canvas of paintings

“…To identify potential matches between different canvases based on the thread distance maps, we adopt an approach similar to that described by [17]. Specifically, we extract a small band of the distance map and take the median along this band (in the direction of the threads) to obtain an estimate of the thread distance signal.…”

Whole-painting canvas analysis using high- and low-level features

“…Assembling x-rays into a virtual single, whole-painting x-ray image produces more accurate thread counts that increases the accuracy of matching of paintings to the same canvas via a common weave pattern [3], but which requires careful accounting of rotation, brightness and contrast discrepancies and smoothly blending the components together. This high-level processing must not affect the detailed thread counting algorithm since it relies on the 2D periodic nature of woven fabric to work.…”

On the Utility of Spectral-Maximum-Based Automated Thread Counting from X-Radiographs of Paintings on Canvas

“…meters) along the same bundle of threads? a suitably normalized cross-correlation of density profiles is used to provide a measure of similarity [3]. cross-correlations internal to large paintings by Matisse are examined, and it is observed that the level of cross-correlation between X-radiographs with shared threads only gradually decays within 2-3 m of separation.…”

“…thus, the location of a strong peak in a cross-correlation curve drawn as a function of the relative shift between two similar curves indicates the relative shift providing the most agreeable alignment. a strong peak in the crosscorrelation of two X-radiograph profiles suggests the two radiographs (and their associated paintings) shared threads on the same canvas bolt [2,3,5,6]. a reasonable question to ask is whether or not the strength of a normalized cross-correlation is related to before an Aquarium from the art institute of chicago.…”

“…values from the 15 Matisse paintings for which data were available are plotted in Figure 6. the formula for normalized cross-correlation from [3] compensates for different amounts of overlap between different X-radiographs in the same row. this is needed because X-radiographs are typically not laid down according to a precise grid and have varying degrees of overlap with their immediate neighbors.…”